RHEOLOGICAL AND TECTONIC MODELING OF SALT PROVINCES

Technological improvements and a more-rigorous research approach have led the petroleum industry to renew and expand its interest in physical modeling of faulting associated with halokinesis. Salt tectonics and the formation of structural hydrocarbon traps can be reproduced in models using viscous polymers for the substratum and frictional plastic granular materials for the overburden. The fault patterns simulated in these dynamically scaled models are remarkably similar to those in depth-converted seismic sections. Scale models are, therefore, useful for generating new concepts and for reconstructing the structural evolution of hydrocarbon traps. Although even unscaled models may help generating ideas, the full transfer of quantitative data requires that models be dynamically scaled to their natural prototypes. Previously, published scaling theory for salt tectonics has erroneously assumed fluid behaviour of the overburden. This paper provides a sound scaling approach for geological deformations involving brittle overburdens on ductile substrata. Rheological data from overburden rocks and salt are compiled and compared to model rheologies using dimensions of laboratory analogs and other, intrinsic material properties. Scaling approaches are compared and rules are formulated for achieving dynamic similarity in models of salt tectonics, including those with synkinematic sedimentation.